The invention relates to an adjusting mechanism, in particular a seat adjusting mechanism for automotive vehicles, comprising a drive member having a toothing and being movable in each of two mutually opposite directions, an actuating member having a neutral position, a guide contour, and two claws movably mounted on said actuating member such that, when the actuating member is moved out of said neutral position in one of said two directions along the toothing of the drive member, one of the two claws meshes with the toothing and the other one is lifted away from the toothing by said guide contour.
An adjusting mechanism of this type is disclosed in Fischer et al. U.S. Pat. No. 5,865,285, wherein the drive member is a gear which is coupled to a seat part to be adjusted through a freewheel brake. When a lever serving as an actuating member is pivoted in any direction out of the neutral position, the one of the claws which then forms the leading claw meshes with the toothing of the gear, so that the gear is rotated and the force is transmitted to the seat part to be adjusted via the freewheel brake. The freewheel brake holds the gear in the position it has reached, when the lever is returned to the neutral position. Thus, the seat part can be adjusted in any desired direction in a step-wise manner by repeatedly rocking the lever. During the return stroke of the lever, the latter is disengaged from the gear because the claw which is then the leading claw is lifted away from the toothing by the guide contour. The claw which at first has been in mesh with the gear could slip over the toothing during the return movement. Then, it would however produce a noise like a ratchet, and this may be disagreeable for the user. For this reason, the known adjusting mechanism provides a spring system which biases the trailing claw away from the toothing during the return stroke of the lever.
However, this construction is relatively cumbersome and further has the drawback that the coupling between the actuating lever and the gear is cancelled as soon as the user interrupts the adjusting movement. Then, the user must at first return the lever to the neutral position in order to re-establish the coupling.
It is an object of the invention to provide an adjusting mechanism of the type indicated above which has simple construction, is easy to operate and the actuating member of which can be returned to the neutral position without producing substantial noise.